Thermodynamic Behaviour of Hydrogen-Powered Hypersonic Ramjets Flying Along Ideal Trajectories.

Abstract

A simulation model for the ramjet propulsion describing the strong coupling of thermodynamic and flightmechanic parameters is presented.The ideal trajectory is subdivided into segments each one representing the solution of a boundary value problem with additionalconstraints for dynamic pressure and minimum fuel consumption. The thermodynamic model of the ramjet comprises a precompression due to the angle of attack, a compression by a multiple shock system, a subsonic diabatic flow and an expansion in a Laval nozzle and along an unsymmetric expansion ramp. The thrust vectoring is realized by analternating control of either geometrics of the diffuser and the Laval nozzle or the angle of attack. Typical numerical results for the ramjet mode of a hydrogen powered TSTO reference vehicle are discussed. Limiting values of the main parameters needed for design purposes of future ramjet propulsion systems and for test stands are given.